Method and apparatus for controlling automatic opening and closing of window of driver&#39;s cab of working vehicle

ABSTRACT

A method and apparatus is provided for controlling the automatic opening and closing of a window of the driver&#39;s cab of a working vehicle in which the automatic opening and closing operations and locking operation of the window are carried out smoothly by detecting the opening and closing stop positions of the window and the operation stop positions of the locking units without fail and with high safety. In the method and the apparatus for controlling the opening and closing of the window in which the window (14) can be moved vertically between the window frame (16) and the top wall (18) by the driving means (34) for the driving cable (28) and pressed against the window frame (16) by the locking units (29L, 29R) during a window closing operation to shut the window, the terminal position for the downward movement of the window (14) during its closing operation and the terminal position for the upward movement of the window (14) during its opening operation are detected as a load current of the driving means (34) for the driving cable (28) exceeding a predetermined threshold value, whereupon the driving means (34) for the driving cable (28) is stopped. The locking stop positions and locking release positions of the locking units (29L, 29R) are also detected as the load currents of the lock motors (44L, 44R) exceeding a predetermined threshold value, whereupon the lock motors (44L, 44R) are stopped.

FIELD OF THE INVENTION

This invention relates to improvements in a method and apparatus forcontrolling the automatic opening and closing of a window of thedriver's cab of a working vehicle, which is suitable for the opening andclosing of the front window of the driver's cab of a constructionmachine such as a hydraulic shovel, crane or the like.

BACKGROUND OF THE INVENTION

In a construction machine such as a hydraulic shovel, crane or the like,the front window can be opened and closed because the glass of the frontwindow (to be referred to as "window" hereinafter) makes it difficult tosee objects outside the driver's cab, communication with an assistantworker is necessary, and so on. That is, guide rails, extending from thewindow frame to the top wall (ceiling) of the driver's cab, are providedso that the window is moved upwardly as it is moved away from the windowframe, by pulling it from the window frame toward the driver, and thenis moved along the guide rails until it becomes parallel to the topwall. This operation is performed manually by the driver, holding one ofthe grips provided on the top and bottom of the window.

Since the weight of the window is about 20 kg, it is not easy for thedriver to open and close the window. Further, as each guide rail isshaped almost like a turned letter L, it is difficult to move the windowsmoothly along the bent portion of the guide rail, and the driver mustopen and close the window in an unnatural posture. Therefore, theinventors of the present invention have proposed an apparatus forautomatically opening and closing this type of window (refer toJP(A)4-36519).

In the above apparatus, guide rails for moving the window vertically areprovided both on the window frame and on the top wall, rollers whichroll along each of the guide rails are provided at the four corners ofthe window, a driving cable provided with a wire ring is connected tothe window, and the window is opened and closed by the drive force of amotor for circulating the driving cable. The opening operation of thiswindow is accomplished as follows. A motor driving switch is firstturned on to rotate the motor, and the window is pulled upwardly by thedriving cable and stored in the guide rails on the top wall. The closingoperation of the window is accomplished as follows. The cable is drivenby the reverse rotation of the motor so that the window is moveddownwardly along the guide rails on the window frame from the guiderails of the top wall. Particularly, when the window is closed, lockingunits are used to press the window against the window frame and shut itafter the window is moved downwardly to face the window frame. Each ofthe locking units is structured such that it engages with a locking pin,provided on the window, only at the time of locking so that it does notinterfere with the movement of the window during the window opening andclosing operations.

In this type of automatic opening and closing mechanism, it is necessaryto carry out the detection of the window opening or closing end positionproperly at the time of opening or closing the window and to surelydetect the locking stop position or the locking release position of thelocking units at the time of locking or releasing the window. However,technical matters related to these have not been disclosed in theautomatic opening and closing mechanism of the prior art. In this case,it is conceivable to use a limit switch as a detection element, but anexcessive load may be applied to the limit switch, depending on its setposition. If the detection depends on the limit switch only, there isthe possibility of causing damage to the driving motor due to theapplication of an overload on the driving system.

SUMMARY OF THE INVENTION

In view of the above problem of the prior art, it is an object of thepresent invention to provide a method and apparatus for controlling theautomatic opening and closing of a window of the driver's cab of aworking vehicle in which the automatic opening, closing and lockingoperations of the window are smoothly carried out by detecting theopening and closing operation stop positions of the window and theoperation stop positions of the locking units without fail, and a highdegree of safety is provided.

According to the present invention, in the method of controlling theautomatic opening and closing of the window, wherein the window of thedriver's cab of a working vehicle is provided between a window frame anda top wall of the driver's cab in such a manner that it can be drivenvertically by a driving means for a driving cable, is moved verticallyby turning on an operation switch, and is pressed by locking unitsagainst the window frame to be shut during a window closing operation;the terminal position for the downward movement of the window during awindow closing operation and the terminal position for the upwardmovement of the window during a window opening operation are detected asa load current of the driving means for the driving cable exceeding apredetermined threshold value, whereupon the driving means for thedriving cable is stopped. In the middle of window opening and closingoperations, the driving means is stopped when the load current of thedriving means exceeds a predetermined threshold value, except that theoperation of the driving means is continued for a predetermined timeafter the starting of the driving means even when the load currentexceeds the predetermined threshold value. After the terminal positionfor the downward movement of the window during a window closingoperation is detected, a predetermined time lag can be provided beforethe starting of the locking units.

The locking stop position and the locking release position of thelocking units are also detected as the load currents of the lock motorsfor the locking units exceeding predetermined threshold values,whereupon the lock motors are stopped. After detecting the lockingrelease positions of the locking units, a predetermined time lag can beprovided before the starting of the driving means for the driving cable.

Further, according to the present invention, in an apparatus forcontrolling the automatic opening and closing operations of the windowwhich comprises guide rails formed between the window frame and the topwall of the driver's cab of a working vehicle; a window movable alongthe guide rails; a driving cable, connected to the window, for movingthe window vertically; a driving means for the driving cable; lockingunits for pressing the window against the window frame to shut thewindow; and a controller for controlling these operations; thecontroller comprises a vertical movement processing unit for detectingthe load current of the driving means for the driving cable to detectthe terminal position for the downward movement of the window during awindow closing operation and the terminal position for the upwardmovement of the window during a window opening operation as the loadcurrent exceeding a predetermined threshold value, and for outputting astop signal to the driving means for the driving cable. The controllerfurther comprises a safety circuit for stopping the operation of thedriving means when the load current of the driving means for the drivingcable exceeds the predetermined threshold value in the middle of awindow opening or closing operation, and a cut circuit for continuingthe operation of the driving means for a predetermined time after thestarting of the driving means even when the load current exceeds thepredetermined threshold value. In addition, the controller comprises adelay circuit for providing a predetermined time lag for the starting ofthe locking units after the terminal position for the downward movementof the window during a window closing operation is detected.

The controller also comprises a locking processing unit and a lockingrelease processing unit for detecting the load current of the lock motorof the locking unit to detect the locking stop position and the lockingrelease position of the locking unit as the load current exceeding athreshold value and for outputting a lock motor stop signal. Inaddition, the controller comprises a delay circuit for providing apredetermined time lag for the starting of the driving means for thedriving cable after the locking release position of the locking unit isdetected.

According to the above constitution, the terminal position for thedownward movement of the window during a window closing operation andthe terminal position for the upward movement of the window during awindow opening operation can be detected as a load current applied tothe driving means for the driving cable exceeding a predeterminedthreshold value. Therefore, the driving means can be stopped withoutfail and at the same time, protected from an application of an excessiveload. Further, the locking stop position and the locking releaseposition of the locking unit can be detected as the load current of thelock motor of the locking unit exceeding a predetermined thresholdvalue. Therefore, the lock motor can be stopped without fail and at thesame time, protected from an application of an excessive load. Theseoperations make it possible to enhance the durability of the lock motorof the locking unit and the durability of the driving means for thedriving cable and at the same time to smoothly carry out window opening,window closing, locking stop operation, and locking release operation.Further, the provision of a delay circuit makes it possible to carry outthese operations even more smoothly. In addition, the provision of asafety circuit and a cut circuit makes it possible to prevent suchinconvenience as the driving means being stopped by a high load currentshortly after the starting of operation, while ensuring safety bystopping the driving means suddenly when a man or an object is caught inthe window during the opening or closing operation of the window.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the configuration of an apparatus forcontrolling the automatic opening and closing of a window of thedriver's cab of a working vehicle according to a preferred embodiment ofthe present invention;

FIG. 2 is a flow chart of a window closing operation;

FIG. 3 is a flow chart of a window opening operation;

FIG. 4 is a diagram explaining a working vehicle equipped with theapparatus of the preferred embodiment for controlling the automaticopening and closing of the window;

FIG. 5 is a perspective view of the apparatus for explaining windowopening and closing operations;

FIG. 6 is a diagram explaining the driving cable;

FIG. 7 is a diagram explaining window open and closed states; and

FIG. 8 is an exploded perspective view of a locking unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the present invention is described in detailwith reference to FIGS. 1 to 8.

The working vehicle equipped with the apparatus for controlling theautomatic opening and closing of the window of this embodiment is ahydraulic shovel 10, as shown in FIG. 4. A window 14, installed at thefront of a cabin 12 forming the driver's cab, can be automaticallyopened or closed.

The cabin 12, as shown in FIG. 5, has a pair of guide rails 20L and 20Ron the window frame 16 and another pair of guide rails 22L and 22R onthe top wall 18, along which the side edges of the window 14 are guided.Slide plates 24L and 24R, which are accommodated in the guide rails 22Land 22R on the top wall and are used to press the window 14 against thewindow frame 16 during a window locking operation, are installed at theleft and right upper end portions of the window 14, respectively. Theslide plates 24L and 24R are driven forwardly in a window lockingdirection by means of the pressing means 26L and 26R, which are arrangedabove the guide rails 22L and 22R, respectively. The locking units 29Land 29R are constituted by the slide plates 24L and 24R and the pressingmeans 26L and 26R, respectively.

To move the window 14 vertically, as shown in FIG. 6, the ends of adriving cable 28 are secured to the connectors 30L and 30R, which arefixed to the left and right side portions of the window 14. Explainingfrom the left side, the driving cable 28, having one end secured to theconnector 30L, extends along the guide rails 20L and 22L toward the rearof the cabin 12, then goes through the unshown guide rails 22R and 20Ron the opposite side, extends downwardly, turns back through an idlerroller 32R, which is provided on the side of the cabin 12 at a lowerposition of the window frame 16, and is secured to the connector 30R.The driving cable 28, whose other end is secured to the right connector30R also turns back through an idler roller 32L and is connected to theconnector 30L. A driving means 34 is provided in such a manner that itengages with the driving cable 28 to drive the driving cable 28. Thatis, sections of the driving cable 28 are made of a geared cable, and thedriving means 34 is constituted by a gear 34G arranged to engage withthe upper and lower geared sections, and a cable driving motor 34M forrotating the gear 34G. Therefore, the connectors 30L and 30R are pulledupwardly, as shown by a solid line arrow S1 in FIG. 6, by rotating thecable driving motor 34M in one direction, and are pulled downwardly, asshown by a broken line arrow S2, by rotating the cable driving motor 34Mreversely. Since the connectors 30L and 30R are attached to the window14, the opening and closing operations of the window 14 are effected bythese movements of the driving cable 28.

The open and closed states of the window 14 are shown in FIG. 7. Theopen state of the window 14 is state A, in which the window 14 liesalong the guide rails 22L and 22R of the top wall 18; the intermediatestate of the window 14 is state B, shown by a broken line in which anupper end portion of the window 14 is located on the guide rails 22L and22R of the top wall 18 and a lower end portion of the window 14 islocated on the guide rails 20L and 20R of the window frame 16; thelocking standby state is state C, in which both upper and lower portionsof the window 14 are held in the guide rails 20L and 20R of the windowframe 16; and the locked state is state D, in which the left and rightupper end portions of the window 14 are pressed against the window frame16 by the locking units 29L and 29R to secure the window 14.

The left locking unit 29L, out of the left and right locking units 29Land 29R, is described in detail with reference to FIG. 8.

The locking unit 29L comprises the slide plate 24L and the pressingmeans 26L. A roller 36L is provided on one side of the slide plate 24Land is guided along the guide rail 22L. An elongated hole 38L is formedin an end portion of the slide plate 24L, and a coupling shaft 40L,projecting from an upper end of the window 14, is inserted into the hole38L to interconnect the slide plate 24L and the window 14. Meanwhile,the pressing means 26L is arranged above the slide plate 24L and has acam plate 42L arranged in the same plane as the slide plate 24L. On oneside of the cam plate 42L, a lock motor 44L and a threaded rod 46L,rotated by the lock motor 44L, are installed. The threaded rod 46L isfitted with a movable nut 48L, and a vertically movable locking member50L is attached to the movable nut 48L. The locking member 50L has a campin 52L which projects toward the direction of the thickness of the camplate 42L and which fits in a cam slot 53L provided in the cam plate42L. The cam slot 53L is shaped such that the locking member 50L canmove downwardly on a slope in a forward direction from the limitposition of its backward movement and then move forwardly horizontally.The slide plate 24L is provided with a locking pin 54L to perform alocking operation, and a locking groove 56L is formed on an undersurface of the locking member 50L. When the locking member 50L movesforwardly from the limit position of its backward movement, it movesdownwardly and engages with the locking pin 54L, and then the slideplate 24L is forced to move forwardly with the advance of the lockingmember 50L, so that an upper end portion of the window 14 is pressedagainst the window frame 16 to tightly close the window 14. The lockingrelease operation of the window 14 is performed by reversing the aboveoperation.

FIG. 1 shows a control unit constituted to optimize such window openingand closing operations. The control unit has a controller 60, forcontrolling the opening and closing operations of the window 14, whichis caused to receive an operation signal from an operation switch 62 forselecting an opening operation or a closing operation of the window 14.In response to this operation signal, the controller 60 outputs asignal, for controlling the cable driving motor 34M, to drive thedriving cable 28 to the opening side or to the closing side according tothe input direction of the operation switch 62.

To the controller 60 are applied: a signal for detecting that the window14 has reached the terminal position of its downward movement in aclosing operation and is in the locking standby state C, a signalindicating that the window 14 has been stored in the top wall 18 in aclosing operation, a signal for detecting the locked state D in whichthe pressing means 26L and 26R have moved the slide plates 24L and 24Rforwardly, and a signal for detecting that the locking members 50L and50R are separated from the slide plates 24L and 24R and have reached thelimit positions of their backward movements.

First, when the window 14 is moved downwardly by a closing operation andits lower end portion reaches the lower ends of the guide rails 20L and20R on the window frame 16, the load current of the cable driving motor34M increases, and a so-called surge current is generated since thewindow 14 cannot move further. The controller 60 detects that the loadcurrent of the cable driving motor 34M exceeds a predetermined value andjudges that the window 14 has reached the terminal position of itsdownward movement and is in the locking standby state C.

Similarly, when the window 14 is moved upwardly in an opening operationand the slide plates 24L and 24R have reached the rear ends of the guiderails 22L and 22R, the load current of the cable driving motor 34Mincreases because the window 14 cannot move further back. The controller60 detects that the load current of the cable driving motor 34M exceedsa predetermined value and judges that the window 14 has reached theterminal position of its upward movement and is in the open state A.That the window 14 reaches the terminal position of its upward movementcan be detected when an upper end portion of the window 14 contacts anunshown fixing member arranged to face the upper end portion of thewindow 14.

Such signals for detecting the terminal positions of the movements ofthe window 14 are used by the controller 60 to surely control thelocking units 29L and 29R as will be described hereinafter.

The limit positions, for the forward and backward movements of thelocking members 50L and 50R of the locking units 29L and 29R, aredetected by the controller 60 through a comparison of the load currentsof the lock motors 44L and 44R and a reference current. That is, whenthe movable nuts 48L and 48R of the pressing means 26L and 26R are movedforwardly to press the window 14 against the window frame 16 in alocking operation of the window 14, contact pressure between the windowframe 16 and a rubber seal around the window 14 increases, whereby themoving resistance of the movable nuts 48L and 48R rises with the resultof an increase in the load currents of the lock motors 44L and 44R,thereby causing a so-called surge current. The limit positions, for theforward movements of the locking units 29L and 29R, can be judged bydetecting that this load current exceeds a predetermined thresholdvalue.

Similarly, by the locking release operation of the window 14, themovable nuts 48L and 48R of the pressing means 26L and 26R are movedbackwardly and are brought into contact with the rear bearings 72L and72R of the threaded rods 46L and 46R, or the locking members 50L and 50Rare brought into contact with the edges of the cam slots 53L and 53R toprevent the backward movements of the movable nuts 48L and 48R,respectively. This prevention force increases the load currents of thelock motors 44L and 44R. The limit positions, for the backward movementsof the locking units 29L and 29R, can be judged by detecting that theseload currents exceed a predetermined threshold value.

The controller 60 comprises a locking release processing unit 76 and alocking processing unit 78 for the window 14, a slack eliminatingprocessing unit 80 and a vertical movement processing unit 82 for thedriving cable 28, a delay circuit 84, a safety circuit 86, and a cutcircuit 88 to process the above input detection signals. The contents ofthese processings are described with reference to the flow charts ofFIGS. 2 and 3.

The closing operation of the window 14 is described with reference toFIG. 2. When the operation switch 62 is switched to DOWN (step 100), thecable driving motor 34M is activated to move the window 14 downwardly(step 102). At this point, an unshown rear locking means which holds thewindow 14 at the open position is released (step 104). Then, it isconfirmed that the window 14 is separated from an unshown rear limitswitch provided on the top wall 18 (step 106), and whether the window 14has moved downwardly and reached the limit position of its downwardmovement is judged by detecting that the load current I_(D) of the cabledriving motor 34M exceeds a predetermined threshold value I_(O) (step108). When the load current I_(D) does not exceed the threshold value,step 108 is repeated to continue the downward movement of the window 14.The operation state of the window 14 is changed from the open state A tothe locking standby state C in FIG. 7 by such processing. When the loadcurrent I_(D) exceeds the threshold value I_(O), it is judged that thewindow 14 has reached the terminal position of its downward movement.Therefore, the vertical movement processing unit 82 of the controller 60outputs a stop instruction to the cable driving motor 34M so as to stopthe movement of the window 14 (step 110). Since the cable driving motor34M is stopped before application of an overload, it is protected froman overload.

A predetermined time lag for the starting of the locking units 29L and29R after the stoppage of the window 14 at the limit position of itsdownward movement is provided by the delay circuit 84. In thisembodiment, this time lag is set to 0.5 second (step 112) to prevent theoccurrence of extremely small vibrations just after the window 14 hasreached the terminal position of its downward movement and to ensureengagement between the locking units 29L and 29R and the slide plates24L and 24R, respectively.

The locking operation of the window 14 is then started by operating theleft and right locking units 29L and 29R independently. That is, thelocking members 50L and 50R are moved downwardly by the operation of thelock motors 44L and 44R to engage the locking grooves 56L and 56R withthe locking pins 54L and 54R, respectively. During this time, theoperations of the lock motors 44L and 44R are interrupted (steps 114 and116). In this embodiment, these operations are interrupted for almost 1second after the starting of the lock motors 44L and 44R. The slackeliminating processing unit 80 of the controller 60, which receives aninterruption signal, generates an output for driving the cable drivingmotor 34M for the upward movement of the window 14 to remove slack inthe driving cable 28 (step 118). Since the amount of slack in the cable28 is small, the driving cable 28 is wound up for a predetermined shorttime. In this embodiment, the cable is wound up for 0.1 second. At thispoint, since the locking members 50L and 50R are held by the threadedrods 46L and 46R, locking is not undone even if the amount of winding istoo large.

Subsequently, the locking processing unit 78 of the controller 60 drivesthe left and right lock motors 44L and 44R to advance the slide plates24L and 24R, respectively (steps 120 and 122). The load currents I_(FL)and I_(FR) of the lock motors 44L and 44R are applied to the lockingprocessing unit 78, which compares these load currents I_(FL) and I_(FR)with a preset threshold value I_(FO) (steps 124 and 126). When it isdetected that these load currents exceed the threshold value I_(FO), thelock motors 44L and 44R are stopped (steps 128 and 130). That is, theleft and right end portions of the window 14 are each pressed againstthe window frame 16, and the rubber seals provided at these portionscontact each other, whereby pressing resistance gradually increases. Dueto this increasing resistance, the load currents I_(FL) and I_(FR) ofthe lock motors 44L and 44R grow, thereby generating a so-called surgecurrent. Therefore, a surge current generated when a predetermineddegree of sealing is reached is taken as a threshold current I_(FO), andat the time when this current is reached, the window 14 is shut withoutfail.

A description is subsequently given of the opening operation of thewindow 14 with reference to FIG. 3. When the operation switch 62 isswitched to UP (step 200), the left and right locking units 29L and 29Rare independently activated to drive the lock motors 44L and 44Rreversely so as to move backwardly the movable nuts 48L and 48R, whichare located at the limit positions of their forward movements,respectively (steps 202 and 204). Thereby, the locking members 50L and50R move the slide plates 24L and 24R, respectively, backwardly toseparate an upper end portion of the window 14 from the window frame 16.Subsequently, as the movable nuts 48L and 48R move backwardly, the camslots 53L and 53R formed in the cam plates 42L and 42R cause the lockingmembers 50L and 50R to move upwardly while moving backwardly,respectively. As a result, the locking members 50L and 50R aredisengaged from the slide plates 24L and 24R, respectively. When thelocking members 50L and 50R are brought into contact with the ends ofthe cam slots 53L and 53R at the limit positions of their backwardmovements or with the rear bearings 72L and 72R, they are stopped.Thereby, the load currents I_(RL) and I_(RR) of the lock motors 44L and44R increase, thus generating a surge current. These load currentsI_(RL) and I_(RR) are applied to the locking release processing unit 76of the controller 60 which compares these load currents I_(RL) andI_(RR) with a preset threshold value I_(RO) (steps 206 and 208). When itis detected that these load currents exceed the threshold currentI_(RO), the lock motors 44L and 44R are stopped (steps 210 and 212).This completes the locking release processing of the window 14. In thisrespect, since the upper end portion of the window 14 which is free fromthe driving cable 28 may vibrate, the window 14 is held on standby bythe delay circuit 84 for about 0.5 second until the vibration state isconverged (step 214). Subsequently, processing is transferred to thevertical movement processing unit 82 of the controller 60, which drivesthe cable driving motor 34M in a cable winding-up direction (step 216).Thereby, the window 14 is moved upwardly and stored in the top wall 18of the cabin 12. The load current I_(U) of the cable driving motor 34M,at the time of rotation for upward movement, is applied to thecontroller 60, which compares the load current I_(U) with a thresholdvalue I_(O) which is a preset reference current to judge whether theload current I_(U) exceeds the threshold value (step 218). When the loadcurrent I_(U) does not exceed the threshold value I_(O), step 218 isrepeated to continue the upward movement of the window 14. When the loadcurrent I_(U) exceeds the threshold value I_(O), it can be judged thatthe upper end portion of the window 14 has contacted a stopper or thelike and has reached the open end position, and hence, the verticalmovement processing unit 82 stops the cable driving motor 34 (step 220).Since the cable driving motor 34M is stopped before application of anoverload, it is protected from an overload. Thereafter, the rear lockingof the window 14 is carried out (step 222) to complete the openingoperation.

According to this embodiment of the present invention, the stop positionof the window 14 can be determined with accuracy while application of anexcessive load current to the driving motor 34M can be prevented,thereby making it possible to carry out the automatic opening andclosing of the window smoothly. Particularly, since a predetermined timelag is provided for the starting of the locking units 29L and 29R afterthe window 14 reaches the terminal position of its downward movement,the locking members 50L and 50R can be engaged with the locking pins 54Land 54R, respectively, after vibration generated right after the window14 reaches the terminal position of its downward movement endscompletely. Therefore, a locking failure can be prevented without failduring the automatic closing operation of the window 14, and the closingoperation can be automated safely. Further, the operations of the lockmotors 44L and 44R are interrupted when the locking members 50L and 50Rengage with the locking pins 54L and 54R, respectively. Since slack inthe driving cable 28 is removed by winding up the driving cable 28during the interruption of the operations, the driving cable 28 can beprevented from falling off of the guide rails 20L, 20R, 22L and 22R.Particularly, during the opening operation, an operation failure due tothe cable play allowance can be prevented.

In this embodiment, since the left and right locking units 29L and 29Rcan be operated independently, the window 14 cannot be partially pressedagainst the window frame 16 to be shut. Particularly, when there is adifference of installation error between the locking units 29L and 29R,due to the production accuracies of the window 14 and the cabin 12 orthe like, or when the locking units 29L and 29R have a production errorthemselves, the window 14 can be shut without fail. Therefore, there isno locking failure.

Moreover, since the limit positions of the forward movement and backwardmovement of the locking units 29L and 29R are detected by a surgecurrent applied to the lock motors 44L and 44R, the contact forcebetween the window 14 and the window frame 16 can be made constant, andan application of an excessive load current can be prevented, therebymaking it possible to improve the durabilities of the lock motors 44Land 44R without a large burden on these.

In addition, the safety circuit 86 is provided in the controller 60,which detects a load current generated in the cable driving motor 34Mwhen a man or an object is caught in the window 14 during an automaticopening or closing operation, stops the cable driving motor 34M, andgives an alarm. Therefore, safety is extremely high. Further, the cutcircuit 88 is provided in the controller 60, which inhibits theoperation of the safety circuit 86 for a very short time at the startingof the cable driving motor 34M or the lock motors 44L and 44R, even whena high surge current generated at the starting of the cable drivingmotor 34M or the starting of the lock motors 44L and 44R is detected.Therefore, an operation failure caused by ensuring safety can beprevented.

INDUSTRIAL APPLICABILITY

This invention is useful as a method and apparatus for controlling theautomatic opening and closing of a window of the driver's cab of aworking vehicle in which the automatic opening, closing and lockingoperations of the window are carried out smoothly by detecting theopening and closing stop positions of the window and the operation stoppositions of the locking units without fail, and high safety isprovided.

That which is claimed is:
 1. A method of automatically controlling anopening and a closing of a window of a driver's cab of a workingvehicle, wherein said driver's cab includes the window and a windowframe, and wherein a window closing operation comprises the stepsof:actuating an operation switch to initiate a window closing operationby applying a load current to a window driving device to initiatemovement of the window via the window driving device; moving said windowvia the window driving device in a downward movement from an openedposition, adjacent a top wall of the driver's cab, toward a lowerterminal position for downward movement of said window; continuing anoperation of the window driving device for a first predetermined timeafter an initiation of movement of the window by the window drivingdevice during the window closing operation, even if a load current ofthe window driving device exceeds a predetermined driving thresholdvalue; detecting the lower terminal position for the downward movementof the window during a window closing operation as a load current of thewindow driving device exceeding said predetermined driving thresholdvalue at a time during the window closing operation after said firstpredetermined time; and stopping an operation of the window drivingdevice upon an occurrence of a detection of the lower terminal position.2. A method in accordance with claim 1, wherein said driver's cabfurther includes locking units for locking the window to the windowframe, and wherein said window closing operation further comprises:upona stopping of the window driving device upon an occurrence of adetection of the lower terminal position, providing a predetermined timelag; and at the end of said predetermined time lag, starting lockingunits for pressing said window to move said window from said lowerterminal position into a closed position against the window frame.
 3. Amethod in accordance with claim 2, wherein each locking unit contains alock motor;wherein the step of starting locking units for pressingincludes applying a load current to each lock motor; and wherein awindow closing operation further comprises the steps of:detecting alocking stop position of a locking unit as a load current of the lockmotor of that locking unit exceeding a predetermined locking thresholdvalue; and stopping an operation of the lock motor of that locking unitupon an occurrence of the load current to that lock motor exceeding thepredetermined locking threshold value.
 4. A method in accordance withclaim 2, wherein each locking unit contains a lock motor;wherein saidwindow driving device includes a drive motor and a drive chain connectedto said window; wherein the step of starting locking units for pressingincludes the steps of:applying a load current to each lock motor to movesaid window from said lower terminal position toward said window frame;interrupting a resulting movement of said window toward said windowframe; actuating said drive motor and said drive chain, during theresulting interruption of movement of said window toward said windowframe, to remove slack in said chain; and then resuming movement of saidwindow toward said window frame.
 5. A method in accordance with claim 4,wherein a window closing operation further comprises the stepsof:detecting a locking stop position of a locking unit as a load currentof the lock motor of that locking unit exceeding a predetermined lockingthreshold value; and stopping an operation of the lock motor of thatlocking unit upon an occurrence of the load current to that lock motorexceeding the predetermined locking threshold value.
 6. A method inaccordance with claim 2, wherein each locking unit contains a lockmotor; and wherein a window opening operation comprises the stepsof:actuating an operation switch to activate the lock motors of thelocking units to initiate a window opening operation by moving thewindow from a closed position toward a locking standby position;detecting, for a locking unit, the locking standby position as a loadcurrent of a lock motor of that locking unit exceeding a predeterminedlocking release threshold value; stopping an operation of the lock motorof that locking unit upon an occurrence of the load current to that lockmotor exceeding the predetermined locking release threshold value; at apredetermined time after the window has been moved from the closedposition to the locking standby position, moving said window, by awindow driving device, in an upward movement from the locking standbyposition toward an opened position adjacent a top wall of the driver'scab; detecting an upper terminal position for the upward movement of thewindow during a window opening operation as a load current of the windowdriving device exceeding a predetermined upward driving threshold value;and stopping an operation of the window driving device upon anoccurrence of a detection of the upper terminal position.
 7. A method inaccordance with claim 1, wherein the driver's cab further includeslocking units for locking the window to the window frame; wherein eachlocking unit contains a lock motor; and wherein a window openingoperation comprises the steps of:actuating an operation switch toactivate the lock motors of the locking units to initiate a windowopening operation by moving the window from a closed position toward alocking standby position; detecting, for a locking unit, the lockingstandby position as a load current of a lock motor of that locking unitexceeding a predetermined locking release threshold value; stopping anoperation of the lock motor of that locking unit upon an occurrence ofthe load current to that lock motor exceeding the predetermined lockingrelease threshold value; at a predetermined time after the window hasbeen moved from the closed position to the locking standby position,moving said window, by a window driving device, in an upward movementfrom the locking standby position toward an opened position adjacent atop wall of the driver's cab; detecting an upper terminal position forthe upward movement of the window during a window opening operation as aload current of the window driving device exceeding a predeterminedupward driving threshold value; and stopping an operation of the windowdriving device upon an occurrence of a detection of the upper terminalposition.
 8. A method of automatically controlling an opening andclosing of a window of a driver's cab of a working vehicle, wherein saiddriver's cab includes the window, a window frame, a top wall, andlocking units for locking the window to the window frame, each lockingunit including a lock motor, and wherein a window opening operationcomprises the steps of:actuating an operation switch to activate thelock motors of the locking units to initiate a window opening operationby moving the window from a closed position toward a locking standbyposition; detecting, for a locking unit, the locking standby position asa load current of a lock motor of that locking unit exceeding apredetermined locking release threshold value; stopping an operation ofthe lock motor of that locking unit upon an occurrence of the loadcurrent to that lock motor exceeding the predetermined locking releasethreshold value; at a predetermined time after the window has been movedfrom the closed position to the locking standby position, moving saidwindow, via a window driving device, in an upward movement from thelocking standby position toward an opened position adjacent a top wallof the driver's cab; detecting an upper terminal position for the upwardmovement of the window during a window opening operation as a loadcurrent of the window driving device exceeding a predetermined drivingthreshold value; and stopping an operation of the window driving deviceupon an occurrence of a detection of the upper terminal position.
 9. Anapparatus comprising:said driver's cab having a window, a window frame,and a top wall; guide rails formed on the window frame and on the topwall, the window being movable along the guide rails; a driving cable,connected to the window, for moving the window vertically; a cabledriving device for driving the driving cable; locking units for pressingthe window against the window frame to shut the window; and acontroller; said controller detecting a load current of the cabledriving device in order to detect, as a load current of the cabledriving device exceeding a predetermined threshold value, either of aterminal position for a downward movement of the window during a closingoperation and a terminal position for an upward movement of the windowduring an opening operation; said controller continuing an operation ofthe cable driving device for a first predetermined time after aninitiation of movement of the window by the cable driving device duringthe window closing operation, even if a load current of the cabledriving device exceeds the predetermined driving threshold value; saidcontroller outputting a stop signal to the cable driving device upon theoccurrence of a detection of a terminal position.
 10. Apparatus inaccordance with claim 9, wherein said controller comprises:a safetycircuit for stopping an operation of the cable driving device when theload current of the cable driving device exceeds the predeterminedthreshold value after said first predetermined time.
 11. Apparatus inaccordance with claim 9, wherein said controller comprises:a cut circuitfor continuing an operation of the cable driving device for said firstpredetermined time after the starting of the cable driving device evenwhen the load current of the cable driving device exceeds thepredetermined threshold value.
 12. Apparatus in accordance with claim 9,wherein said controller comprises:a vertical movement processing unitfor detecting the load current of the cable driving device in order todetect the terminal position for the downward movement during a closingoperation and to detect the terminal position for the upward movement ofthe window during a closing operation as a load current exceeding apredetermined threshold value, and for outputting a stop signal to thecable driving device.
 13. Apparatus in accordance with claim 12, whereinsaid controller further comprises:a safety circuit for stopping anoperation of the cable driving device when the load current of the cabledriving device exceeds the predetermined threshold value.
 14. Apparatusin accordance with claim 13, wherein said controller further comprises:acut circuit for continuing an operation of the cable driving device forsaid first predetermined time after the starting of the cable drivingdevice, even when the load current exceeds the predetermined thresholdvalue, said cut circuit inhibiting operation of said safety circuit forsaid first predetermined time.
 15. An apparatus according to claim 14,wherein the controller further comprises a delay circuit for providing apredetermined time lag for a starting of the locking units after theterminal position for the downward movement of the window during awindow closing operation is detected.
 16. An apparatus according toclaim 15, wherein the controller further comprises a delay circuit forproviding a predetermined time lag for a starting of the cable drivingdevice after the locking release positions of the locking units aredetected.
 17. An apparatus according to claim 9, wherein the controllercomprises a delay circuit for providing a predetermined time lag for astarting of the locking units after the terminal position for thedownward movement of the window during a window closing operation isdetected.
 18. An apparatus according to claim 9, wherein the controllercomprises a delay circuit for providing a predetermined time lag for astarting of the cable driving device after locking release positions ofthe locking units are detected.
 19. An apparatus comprising:saiddriver's cab having a window, a top wall, and a window frame; guiderails formed on the window frame and on the top wall, the window beingmovable along the guide rails; a driving cable, connected to the window,for moving the window vertically; a cable driving device for driving thedriving cable; locking units for pressing the window against the windowframe to shut the window; and a controller, wherein the controllercomprises:a locking release processing unit for detecting a lockingrelease position of the locking units by detecting when load currents oflock motors of the locking units exceed a predetermined threshold value,and for outputting a lock motor stop signal, and a delay circuit forproviding a predetermined time lag for the starting of the cable drivingdevice after the locking release positions of the locking units aredetected.
 20. Apparatus in accordance with claim 19, wherein saidcontroller further comprises:a locking processing unit for detecting alocking stop position of the locking units by detecting when loadcurrents of lock motors of the locking units exceed a predeterminedthreshold value, and for outputting a lock motor stop signal.